Pneumatic tires featuring pitch variations in their tread patterns are known in the art (see, for example, Japanese Unexamined Patent Application Publication Nos. H11-291714A, 2011-213348A and 2007-168572A). Japanese Unexamined Patent Application Publication No. H11-291714A discloses a tire in which wet performance is improved via specific pitch lengths, lateral groove angles of inclination, and lateral groove areas. Japanese Unexamined Patent Application Publication No. 2011-213348A discloses a tire in which noise performance is improved via specific pitch ratios in a pitch sequence. Japanese Unexamined Patent Application Publication No. 2007-168572A discloses a tire in which noise performance is improved via specific pitch lengths and lateral groove widths.
In the tires disclosed in Japanese Unexamined Patent Application Publication Nos. H11-291714A and 2007-168572A, the angles of inclination or areas of the lateral grooves or the widths of the lateral grooves must also be specified in addition to the pitch length, resulting in a complicated design. Moreover, while these tires exhibit improved wet performance or noise performance, it is unclear whether they exhibit improvement in other types of performance, such as steering stability or rolling resistance on dry road surfaces.
In the tire disclosed in Japanese Unexamined Patent Application Publication No. 2011-213348A, only the pitch ratios between multiple pitches unambiguously determined by pitch length are specified. Therefore, although noise performance is improved by the incorporation of the pitch variations, which are intended to improve noise performance in the first place, it is unclear whether there is any improvement in steering stability or rolling resistance on dry road surfaces.